Validate that definitions only contain valid parameters for type

[mikewilli]

A typo like data_sources vs data_source can go unnoticed in a metric config like this:

[metrics.whatever]
data_sources = "my_data"

This parameter should be data_source (singular), but instead it is ignored and so an unrelated error is thrown in CI that doesn't point directly to the problem.

We should add validation to the definition classes that ensures all keys specified in the TOML are valid for the class. This validation also needs to have a list of "extra" keys that are valid for any class because there are additional keys added to certain configs for use outside of metric-config-parser etc. that we need to continue allowing (e.g., deprecated).

Perhaps this validation could be a function in a parent class to all of the definition classes so that each inherits it by default (and can override if needed -- perhaps for the "extra" keys valid for that class?).